Automotive vehicle



Nov. 5, 1946.

F. A. WATSON ,410,557

AUTOMOTIVE VEHICLE Filed Aug. 23, 1943 7l Sheets-Sheet 1 Iwan/0T WMA/Awww.

NGV- 5 1946- F. A. WATSON AUTOMOTIVE VEHICLE Filed Aug. 23, 1943 7 Sheets-Sheet 2 Nov. 5, 1946. F. A. wA'rsoN AUTOMOTIVE VEHICLE Filed Aug. 23, 1945 '7 Sheets-Sheet 5 Nov. 5,1946. F. A. wATsoN AUTOMOTIVE VEHICLE Filed Aug. 23, 1943 7 Sheets-Sheet 4 I l Merval-07" @an/f A- Wan/:S 0 I@ y /af NQ 5 i946. F. A. WATSON AUTOMOTIVE VEHICLE Filed Aug. 25, 1943 '7 Sheets-Shea?. 5

F. A. WATSON ,N557

AUTOMOTIVE VEHICLE Filed Aug. 23, 1943 7 Sheets-Sheet 6 Nw., 5, EM., F. A. WATSON AUTOMOTIVE VEHICLE Filed Aug. 23. 1945 7 Sheets-Sheet 7 u; Elan A. www@ Patented Nov. 5, 1946 UNITED4 STATES PATENT OFFICE AUTOMOTIVE VEHICLE Frank A. Watson, Chicago, Ill. y Application August 23, 1943, Serial No. 499,725

9 Claims.

This invention relates generally to automotive vehicles and in particular to a vehicle of heavy duty type such as a truck or bus, in which a front drive axle is provided with dual wheel assemblies pivotally movable to conform to the contour of the road surface over which the vehicle is operating.

Dual wheel assemblies now commonly used are generally applied to the non-steering wheels of a vehicle and supported for rotation together. It is common practice to have dual wheel assemblies on a rear axle but in these assemblies the dual wheels are usually supported on a common hub unit and incapable of relative rotation to compensate for different sized tires being used on the dual wheels, or for one of the tires travelling a greater distance than the other tire when the vehicle is maneuvered out of a straight line path. With the wheels thus assembled their rotation together is accomplished Vby the slipping of one wheel relative to the road surface. This slipping is objectionable due to the fact that tire wear is accelerated by the slipping action.

By vi ue of the wheels being rotatable as a unit it s apparent that these wheel assemblies are incapable of being used for steering purposes. As a result trucks and buses now in use have dual wheel assemblies only on the rear axle and single wheels on the front axler regardless of the fact that the load may be equally distributed on both axles. The tires on the single steering wheels, therefore, are continuously subjected to an overload, or at least are always maintained near the maximum limit of their safe carrying capacity.

It is an object of this invention, therefore, to provide an improved automotive vehicle of heavy duty type.

'A further object of this invention is to provide a vehicle having dual wheel assemblies throughout so that the vehicle load is equally distributed over all of the wheel tires.

A further object of this invention is to provide a dual'wheel assembly for a front axle in which the wheels are pivotally movable together for steering purposes and supported for relative rotational movement.

Another object of this invention is to provide va dual front wheel drive assembly in which the dual wheels are pivotally movable together in a vertical plane to accommodatey themselves to unevenaoad surfaces.

A still further object of this invention is to provide a brake system for a dual wheel assembly having relatively rotatable wheels, in which brake portions on each wheel are constructed and as- (cl. iso- 24) on the actuation of a common fluid pressure unit. A feature of this invention is found in the provision of aJ dual wheel front axle drive assembly in which the vehicle engine is supported at one end directly on the front axle and rotatably supported at its opposite end on the vehicle frame to provide for its movement with the front axle.

Yet another feature of this invention is found in the provision of a dual wheel front drive assembly in which the dual wheels are supported together for pivotal movement in both horizontal and vertical planes and connected with a drive shaft by means including a diierential mechanism to provide for their relative rotation.

A still further feature of this invention is found in the provision of a dual front wheel drive assembly in which the wheels are supported on a spindle pivotally movablev in one direction about a'vertical axis means and in a direction normal to such one direction about a horizontal axis means, with the two axis means being located substantially intermediate the dual wheels. Driven connection of the wheels with a drive shaft is accomplished by means including a differential mechanism carried on the spindle.

Further objects, features and advantages of this tive assembly of a dual front wheel drive assembly therewith;

Fig. 2 is an enlarged sectional view taken on the line 2-2 in Fig. 1 showing the dual front wheel drive assembly of this invention;

Fig. 3 is a sectional view taken along the line 3 3 in Fig. 2;

Fig. 4 is a view partly in section as seen along the line 4--4 in Fig. 2;

Fig. 5 is a sectional view taken on the line 5-5 in Fig. 1 with parts broken away to more clearly show the assembly relation of the dual front wheel assembly with the front axle and the support of the vehicle engine on the front axle;

Fig. 6 is a sectional view of the front wheel assembly as seen along the line 6 6 in Fig. 4 and showing the wheels in a turning position;

Fig. '7 is a. perspective view of a part of the front wheel drive assembly; and Fig. 8 is an exploded perspective view of the members, the dual front wheel drive assembly y q autres? which provide for the pivotal movement of the wheels in vertical and horizontal planes.

Referring to the drawings the improved automotive vehicle of this invention is shown in Figs.

1. 2 and 5 as including a substantially rectangular horizontal frame or chassis l5 which extends completely about the .drive and control mecha.-

nisms of the vehicle to function as a protective bumper for these parts. The chassis I5 is suitably reinforced by transverseand longitudinal frame members, only two longitudinal members I6 being illustrated in Fig. 1 for the purpose of clarity. s

The vehicle engine l1 is supported pn cross bars I8 carried on a sub-frame I9 which is seengine driving torque and of supporting the front end of the engine I1 while permitting free movement of the axle housing 22 to accommodate itself to road surface irregularities as will be later explained. A clutch operating mechanism 21 and clutch 21a together with the transmission 28 are mounted on the sub-frame I9 in driven association with the engine i1 in a usual manner, a clutch pedal being indicated at 30. The drive shaft 29 from the transmission 28 is aligned with and connected with the front axle drive shaft 3| to provide for the direct transmission of power to the drive shaft 3i without the usual propeller shaft and universal joints.

As illustrated in Fig. 1 the vehicle includes 4 .m bliesr Since thefront wheel assemblies are simi lar in construction only one of them will be referred to in the following detailed description.

A front wheel assembly includes the steering head 32, previously explained, and a steering frame or yoke member 46 (Figs. 2, 3 and 8) The yoke member 46 is integrally formed with a vertically extending portion 41 of a ysubstantially ring shape having a-top boss portion 48 and a U-shaped bottom 49, and a horizontally projected quadrant 5| with a steering knuckle 52. The boss portion 48 and U-shaped bottom 49 have coaxially aligned Lbores 53, with the vertifront dual wheel drive assemblies and dual rear wheel assemblies 45 associated with a rear axle 50.

Each front dual wheel drive assembly includes a steering head 32 of the so-called Elliott type (Figs. l, 2 and 8) which comprisesa tubular body member 33 positioned about andsecured to the axle housing 22, and oppositely arranged goosenecks having horizontal portions or jaws 34 extended outwardly in an axial direction from the tubular body member 33. As` clearly appears in Fig. 2 the jaws 34 are vertically spaced from each-other with each jaw having a vertical bore 35 which are in relative coaxial alignment. 'I'he upper jaw 34 of each steering head 32 is formed with a supporting arm 36 projected inwardly over the tubular body portion 33. A leaf spring 31 is connected at each end with an arm 36 by a spring shackle 38. l

The upper part of the spring 31 is received in a channel member 39 (Fig. 5) and is retained in the channel member by a supporting plate 4| and U-shaped clamping bolts 42. A second channel member 43 is secured in a superposed position on the `menrber.19 by vangle members 40. Carried on the top channel member 43 is a semi-circular frame member 44 composed of a heavy plate metal and extended transversely of the chassis l5. The end peripheral portions of the semi-circular frame member 44 are secured to corresponding semi-circular portions of the chassis l5 as is clearly illustrated in Figs. 1 and 5. The frame or plate member 44 thus serves the dou-ble function of supporting the forward end of the chassis l5 on the front axle housing 22 and of forming a housing or guardfor the axle housing and the front dual Wheel, @55619- tion within the jaws 434 a bore 53 in the steering frame is adjacent a corresponding jaw 34 in the steering head withall of the bores 35 and 53 being in coaxial alignment. This relative position of the steering head 32 and the steering frame 46 is maintained by .the insertion of a king pin 54 in each pair of corresponding bores 35 and 53, a bushing or bearing 56 being located in a bore 35 to rotatably support a king pin 54.

The king pins 54 are secured for pivotal movement with the steering frame 46 by an associated tapered pin 55 extended through aligned openings formed in a king pin and in the steering frame 46 through the wall of each bore 53. It is seen, therefore, that on manipulation of the steering knuckle 52 the steering frame 46 is pivotally moved about the king pins 54 in a horizontal plane. Actuation of the steering knuckle 52 is accomplished by its connection in a ball and socket joint 51 (Figs. 1 and 2) with a steering rod 56 suitably connected with a steering wheel 59 for the vehicle.

As best shown in Figs. 3 and 8 the steering frame 46 at the ring portion 41 is provided with a pair of ears 6| oppositely extended inthe same axial direction and in a horizontal plane. An ear 6| is constructed for reception between the legs of a corresponding U-'shaped lug 62 oppositely arranged on a gear case 63 integrally formed with a spindle 64 for dual wheels 66 and 61. The legs of each lug 62 have aligned holes therethrough for receiving a pivot pin or stub shaft 66 which is also extended through a hole in a corresponding ear 6| on the steering frame 46. The extreme end of each ear 6| is extended through an opening provided in the connecting portion 69 between the legs of a lug 62.

Each pivot pin 68 is maintained in position within a corresponding ear 6| 'and lug 62 by ya.

setscrew 1| threaded in a lug 62 for frictional engagement with a pin 68. It is thus seen that the combination gear case and spindle 63--64 is supported at the pivot pins 66 for pivotal movement with the steering frame 46 in a horizontal plane, and for pivotal movement about the pins 68 in a vertical plane independently of the steering frame 46.

'Ihis double pivotal movement of the combination gear case and spindle 63-64 is clearly apparent from a consideration of Fig. 8. As-previously explained the steering head 32 is iixed on the front axle housing 22 with the horizontal jaws 34 in a vertically spaced relation. On insertion of the steering frame 46 between the jaws 34 the upper boss portion 48 and lower portion 49 of the steering frame are adjacent to a correspending jaw 34. On extension of the pins 54 within the aligned openings 35 and 53 in these adjacent corresponding parts, the steering frame is rotatably supported on the steering head 32 for pivotal movement in a horizontal plane about the vertically extended pins 64. With the steering head 32 and steering frame 46 assembled in this manner the gear case-62 of the combination gear case and spindle 63-64 is pivotally connected with the steering frame by the coacting engagement of a corresponding ear 6| and lug 62 and the insertion of a pin 66 therethrough. By virtue of the ,pin 66 heilig extended in a horizontal plane the combination gear case 63' and spindle 64 is pivotally movable in a horizontal plane with the steering frame-46 relative to the steering head 32, but movable in a vertical plane independently of the steering frame 46 and regardless of the pivotal position of the steering frame 46 relative to the steering head 32. In other words, this relative assembly and construction of the steering head 32, steering'frame 46 and combination gear case and spindle member 66-64 provides for a concurrent pivotal movement of the combination member in both vertical and horizontal planes.

As shown in Fig. 8 the ring portion 41 of the steering frame 46 is formed at one side with a pair of vertically spaced lugs 12 extended in a direction oppositely from one of the lugs 6|. The lugs 12 are formed with aligned openings 13 for receiving a pin 14 by which a drag link 15 is `povotally connected at one end with the steering frame 46. The opposite end of the drag link 15 is connected with like lugs 12 formed on a steering frame for the opposite dual wheel assembly corresponding to the wheels 66 and 61. The steering frame 46 for this opposite dual wheel assembly is constructed in all respects thesame as the steering frame 46 except for the elimination of the quadrant `5| and steering knuckle 52 for reasons which are believed to be obvious.

Secured by screws 16 to the back or right side of the gear case 63, as viewed in Fig. 2, is a combination gear case cover and brake backing plate 11. The plate 11 has an offset portion 16 at its inner periphery to accommodate a grease retainer ring 19 and an offset portion 6| at its outer periphery to receive brake rings 62 and 63 which will be later described. The retainer ring 19 is mounted about a stepped hub or sleeve unit 64 rotatably supported on the spindle 64 by roller .bearings 66 and 61. Integrally formed with the sleeve unit, 64 and at the extreme left end thereof as viewed in Fig. 2, is a gear ring 66 which is located between the back of the gear case 63 and the backing plate 11. The sleeve is maintained in an axial position on the spindle 64 by a hexagonal nut 85 threaded on the endof the spindle and locked in a usual manner by a coacting AWasher 69.

A stepped 'hub' 9| for the inner wheel 61 is rotatably supported over an enlarged section of the sleeve unit 64, with the hub 9| terminating at one end in an integrally formed gear ring 92 rotatableabout a reduced section 93 ofthe sleeve 64. 'Ihe gear 92 is held in position axially of the sleeve by the coacting engagement of mating sleeve and hub portions which form a shoulder 60 at the junction of the enlarged part of the sleeve with its reduced section 93. 'I'he opposite end of the hub 9| is offset, for mating engagement with the offset 18 in the backing' plate 11. Integral with the hub at such opposite end is a wheel plate 94 for the wheel 61 having an axially extending annular flange 96 atitsouter periphery constructed for connection with the wheel rim by bolts 61.

Also rotatable on the reduced section 93 of the sleeve 64, and." at the end o! the sleeve in an axially spaced relation with is a gear ring 66. The gear ring 66 is assembled on the sleeve 64 at the outer or free end of the spindle 64 and is held against axial movement on the sleeve in'one direction bya locking nut and washer assembly 99. Axial movement of the gear 96 in an opposite direction is prevented by a circumferential shoulder portion |0| -formed on the reduced section 93 of the sleeve 64 .between the gear 66 and the gear62. On the shoulder'section |0| are mounted differential gears |02 rotatably supported on screws |03 radially extended from the sleeve 64 and secured thereto by an associated nut |04. 'I'he gears|02 coact with the ring gears 92 and 96 in the conventional differential gearing manner.

'I'he hub |06 for the outer wheel 66 is rotatably supported on the hub 9| for the inner wheel 61 and extends over the gears |02 to completely enclose these gears within the wheel assembly and between the gears 92 and 96. cured to the gear 96 by screws |01 so as to be rotatable therewith. A spring cover |05 is received within the blank side of the gear 98 to cover the outer end of the wheel spindle 66 and the associated assembled parts. 'I'hus considering the sleeve 64|4 as a driven unit the relativie assembly of the gears 92, 96 and |02 provides a differential mechanism between the wheels 66 and 61 which is carried on the spindle 66 and completely enclosed within the dual wheel assembly.

The gear mechanism for driving the gear ring 86 on the sleeve 64 from the drive shaft 3| will now be described. The gear case 63 adjacent its upper end, as viewed in Figs. 2 and 8, is provided with an inverted cup-shaped projection |06 for receiving a bearing |09. oppositely arranged vertically downwardly from the cup-shaped projection |06 is an opening for a bearing 2, the opening being formed in a. horizontally and downwardly extended cap ||3 integral with the gear case 63. The cap |I3 is open at the back side of the gear case 63 and constitutes a part of the housing for a. gear ||4 mounted on a ver.- tical` shaft ||6 and in meshing engagement with the sleeve gear 66. The shaft ||6 is of a stepped construction and rotatable in the bearings |09 and ||2, bearings ||1 and ||6 oppositely positioned in a gear case insert H9, and a bearing |2| adjacent the lower end of the shaft ||6, as viewed in Fig. 2,.carried in a cover plate |22 for the bottom of the cap I3. The lower bearing |2| is held in vertical coaxial alignment with the remaining supporting bearings for the shaft 6 by a tted positioning of the cover plate |22 within the cap and against the backing plate 11, and the securing of screws |23. Thus as shown in Fig. 2 the gears 66 and ||4 are completely enclosed between the back of the gear case 63, the cover plate |22 and the backing plate 11.

I'he gear case insert ||9 (Figs. 2, 3 and 7) is of a substantially cylindrical shape having a closed rounded end and an oppositeopen end |20, with the opposite sides of the insert in which v'the bearings ||1 and ||8 are located being of a flat form to provide for the assembly of these bearings in frictional engagement with the corresponding-bearings |06 and in the gear case 63. Mounted on the vertical shaft ||6 and within the gear case insert ||9 is a gear |26 frictionally engageable with the bearing ||8 and in the gear ring 62.

The hub 06 is sethe plate |22 to the cap by meshing engagement with a gear |29 mounted on a stub shait |3| which is extended from the axle housing 2-2 and into the gear case insert ||9 at its open end |20 (Figs. 2 and 3). The relative assembly and construction of the ear lugs 62 of the gear case and the gear case insert ||9 is such that when the gear case 63 is pivotally connected at the pins 68 with the steering frame 49,-the shaft H8 is in verticalcoaxial alignment with the pivot pins 54 connecting the steering frame with the steering head 32.

The drive shaft gear |29 (Fig. 3) is-mounted on a stub shaft |3| journaled on a roller bearing A |32 carried in a cover plate |33 for the open end of the insert ||9, the cover |33 being secured to the insert by screws |34. Adjustment of the bearing |32 relative to the gear |29 is accomplished by the insertion of shims |36 between the cover |33 and the insert end |20.

Connection of the drive shaft 3| with the stub shaft |3| is made through a universal joint |38 having one hub |33 splined with the stub shaft, with the relative axial positions oi the stub shaft |3| and hub |39 being maintained by a tapered pin |4| extended therethrough. The opposite hub |42 of the universal joint is in splined engagement with the drive shaft 3| vbut axially slidable relative to the shaft 3|. A plate member |43 is secured over the outer or free end of the axle housing 22 and is provided with a vertically extended opening |44. The hub |39 of the universal joint |38 is in bearing engagement with the vertical sides of the opening |44, as shown` in Fig. 3, but is free to oscillate in a vertical direction between the ends of the opening |44 as shown in Fig. 2. The gear |29 is thus pivotally movable in a vertical plane with the gear case 63 and gear case insert H9, while the stub shaft |3| is maintained in axial alignment with the drive shaft 3 i In the operation of the dual front wheel drive assembly oscillation or turning movement of the steering frame 46 in a horizontal plane by operation of the vehicle steering wheel 59 moves the combination gear case and spindle member 63--64 and all of the mechanism attached thereto as a unit. During such oscillation or turning movement the gear |28 rolls relative to the gear |290. and the gear ||4 relative to the gear 88, by virtue of the shaft IIE being in coaxial alignment with the pivot pins 54.

Further the different relative distances travelled by the wheels 66 and 61 during a, turning movement is accomplished without any scufllng or dragging of the wheel tires because of the diiferential gears 92, .98 and |02. This same diiferential action takes place when the wheels 86 and I6l are travelling over road surfaces of different elevation such as the usual crowned road illustrated in Fig. 5. The differential mechanism while permitting either of the wheels to overrun the other also provides for the application of an equal driving force to each wheel.

The assembly of the steering head 32 within the inner wheel 81 with the jaws 34 extended substantially to the outer wheel 69 places the pivot pins 54 in a vertical plane adjacent the vertical plane of the pivot pins 68 which are located centrally between the wheels 58 and 61. This arrangement of the pivot pins 54 and 68, together with a relatively wide vertical spacing of the jaws 34, eliminates the bending moment on the drive shaft 3|, stub shaft |3| and spindle 54, and further reduces the frictional pressure at the pivot pins 54.

The central position of the pivot pins 54 and V9|! betweenfthe dual wheels effectively balances the pivotingtorque or the wheels and further divides and balances the shocks resulting when the wheels meet with any road obstruction. This effectively reduces shimmy in the wheels which is one of the major faults of dual steering wheels. Further by this construction I am able to obtain 45 pivoting angles as compared with 37 angularity in conventional axles. The pivoting action of my duahsteering wheels, which are also drivers, elimmates the nre drag of nxed wheeis which is known to reduce the life one-half in mountainous roads having almost continuous twists and turns. From a consideration of Figs. 2 and 3 it is seen that the pivot pins 88 are centrally located between the wheel tires so that the load on the vehicle is equally supported on the tires.

Since lthe wheels 86 and 6l are free to pivot on the pivot pins E8 to automatically conform to changing road surfaces, as shown for a crowned road in Fig. 5, an even support of the Vehicle load on the wheel tires is maintained at all times of vehicle travel. This pivotal action of the wheels also provides for a reduction in the impact on a. tire resulting from the striking of a road object since the tire is able to ride over the object without having to lift the companion tire an equal height out of contact with the road.

The brake system for the whee1s'66 and 91 includes the brake rings 82 and 83, previously/ mentioned, which are located in the outer peripheral offset 8| of the backing plate 11 (Fig. 2). The ring 82 is integrally formed with a plurality of angularly spaced studs or extensions |49 projected axially from one side of the ring into corresponding openings formed in the radially extended part of the offset 8|. Secured to the opposite side of the brake ring 82 is an annular brake shoe |5|. The extensions |49 are slidably supported for axial movement in the offset 8|.

A disc-like piston |52 is carried at the free or outer end of each extension |49 for cooperative associationwith a corresponding pressure cylinder |53 concentrically arranged relative to an extension I 49-and secured at its lower end to the outside of the offset 8|, the extension |49 acting as a piston rod for the piston |52. The top of the cylinder is closed by a cover plate |54, with a space in each cylinder and piston assembly formed between the piston |52 and a, corresponding cylinder cover |54 being interconnected by pipe lines |56 connected to a main line |51, which in turn is connected with a master fluid cylinder (not shown) of a fluid braking system which includes the brake pedal |58 shown in Fig. 1.

On operation of the brake pedal |58 the iiuid pressure in the lines |56 and |51 and in the cylinders |53 is increased by the action of the master cylinder, in a manner well known in the art, to in turn move the pistons |52 and brake ring 82 in an axial direction toward the right, as viewed in Fig. 2, for a purpose which will appear later. This movement of the pistons |52 and brake ring 82 takes place against the action of a spring |60 arranged in compression between each piston |52 and the bottom of an associated cylinder |53.

The brake ring` 93, which is assembled within the offset 8| with the brake ring 82, has a flat side adjacent the brake band |5| of the brake ring 82. The opposite side of the brake ring 83 is integrally formed with a plurality of angularly spaced lugs |59 which are slidably movable in an axial direction through corresponding openings 9 in the flange or wheel plate 64 of the inner whee1 61. From a consideration of Fig. 2 it is seen that the brake rings 82 and 63, with the brake band |5| therebetween are completely enclosed by the offset 8| and cooperating portions of the ywheel plate 94 and its axial annular flange 96, the wheel plate 94 being in back to back slidable engagement with the backing plate 11. The brake ring movable to stop positions againsta. corresponding side of the whee1 plate 94.

Normally the brake ring |62 is releasably held in a stop position and the brake ring 62 out of a stop postion with the wheel plate 94 by a plurality of hat springs |64 each of which has one end biasing the brake ring |62 toward the whee1 plate 94 and an opposite end secured to the Wheel plate |94 `by a cap screw |66. The brake rings 83 and |62 are rotatable with the wheel plate 94 and in turn with the inner whee1 61.

A brake shoe ring |61 is secured by screws |66 to the wheel plate |69 of the outer whee1 66, which wheel plate is integral with the outer wheel hub |66. The whee1 plate |69 at its outer periphery has-an axially extended annular ilange |10 positioned about the brake ring |62 and brake shoe |61, the flange terminating, adjacent the inner whee1-plate 94 so that the brake ring |62 and brake shoe |61 are completely enclosed between the inner wheel plate 94 and the outer wheel plate |69, with the brake shoe |61 rotatable with the wheel plate |69. Radially extended from the iiange |10 is an annular ilange |1| t'o which the rim of the outer whee1 66 is connected by bolts |12.

In a normal released position of the above described brake rings 82, 83 and |62 and the brake shoes |5| and |61, the brake shoe |5| is releasably held out of a frictionally engaging position with the brake ring 83 by the springs |66 in the pressure cylinders |53, while the brake ring 62 is releasably held out of a frictional engaging position with the brake shoe |61 by the springs |64. On operation of the master cylinderby the brake pedal |58 to supply uid under pressure to the cylinders |53 the brake shoe |5| engages and moves the brake ring |62 against the brake shoe |61. Both the brake ring 83 and brake shoe |5| are in frictional engagement, prior to the engagement of the brake ring |62 and brake shoe |61, but this initial engagement is very slight and without any apparent braking effect on the inner wheel 61. After the brake ring |62 and brake shoe |61 are frictionally engaged both wheels 66 and 61 are concurrently braked, the inner wheel 61 by the frictional engagement of the rotating ring 83 with the stationary brake shoe 5| and the outer wheel by the frictional engagement of the brake ring |62 with the brake shoe |61.

Because of the connection of the pressure cylnders |53 with a common master cylinder a substantially equal pressure is applied over al1 parts of the brake ring 82 and in turn over the brake shoe |61. Separate frictional braking is thus effectively applied to each of the wheels 66 and 61 over relatively large braking surfaces, with the braking action being substantially simultaneous. On release of the brake pedal |56 the brakes on andas? l0 both wheels are released together by the concurrent reductionaofjthe pressure in the cylinders |53 and the\action of the springs |60 and |64. As a result, during a complete brake action the full braking torue is always divided between the wheels 66 and 61.

From a consideration of the above description it is seen that the invention provides an automotive vehicle of heavy duty type, in which the load is capable of being\equally distributed over all of the vehicle tires by the provision of an improved front dual wheel assembly. Although the w .Y w-heels in this assembly are relatively rotatable their positive braking is accomplished by individual `brakes relatively assembled so as to be completely enclosed within the wheel assembly and concurrently'operated from a common master cylinder. The differential mechanism providing for a relative rotation between the front dual wheels is also enclosed within the wheel assembly and supported entirely on the wheel spindie, to provide in all a compact wheel assembly adapted to be positioned within the same space available for dual wheel assemblies now used commercially.

The wheel driving mechanism is completely free of the pins 54 and 66 so that any wear on these pins in no way changes the relationship of the related parts of the driving mechanism. Conversely the pins 54 and 68 are not affected in any manner by wear or adjustments to the driving mechanism. The driving mechanism and brake system are completely enclosed within the confines of the wheels 66 and 61 so as to be protected against possible injury by striking obstructions, loading docks and the like. Also the wide spacing or vertical distance between the pivot pins 54, together with the location of the pivot pins 68, intermediate the wheels 66 and 61 permits the wheels to absorb heavy shocks without displacement or injury to these pins and the parts which they connect.

Although the invention has been described with respectA to a preferred embodiment thereof it is to be understood that it is not to be so limited since modifications and changes can be made therein which are Within the full intended scope of this invention as defined by the append? ed claims.

1. A'dual front wheel drive assembly including an axle housing, a drive shaft, a yoke member, a spindle for rotatably supporting dual wheels.- pivotall means for supporting said yoke member on said axle housing for pivotal movement in a horizontal plane, means for supporting said spindle on said yoke member for pivotal movement in a vertical plane, and means operatively connecting said wheels with said drive shaft. J

2. A dual front wheel drive assembly including an axle housing, a drive shaft, a yoke member, a spindle for rotatably supporting dual wheels, pivotal means for supporting said yoke member on said axle housing for pivotal movement in a horizontal plane, second pivotal means supporting said spindle on said yoke member for pivotal movement in a vertical plane, with said second pivotal means being in the plane of said spindle and located substantially intermediate said dual wheels, and means operatively connecting said wheels in a driven relation with said drive shaft.

3. A dual front wheel drive assembly including an axle portion, a drive shaft, a frame member.

.11 f means pivotally supporting said frame membe on said axle fo'r movement about a vertical axis, a spindle for rotatably supporting dual wheels, means pivotally supporting said spindle on said frame member for pivotal movement about a horizontal axis, and means operatively connecting said drive shaft with said dual Wheels including a differential mechanism carried on said spindle.

4. A dual front wheel drive assembly including an axle housing,4 a drive shaft, a yoke member, pivotal means for supporting said yoke member on said axle housing for pivotal movement in a horizontal plane, a spindle for rotatably supporting dual wheels, a second pivotal means for supporting said spindle on said yoke member for pivotal movement in a vertical plane, `with said first pivotal means being located substantially intermediate saiddual wheels, and means connecting said drive shaft with said dual wheels including a differential mechanism carried on said spindle. l

5. A dual front wheel drive assembly including an axle housing, a drive shaft, a yoke member, a spindle for rotatably supporting dual wheels, supporting means including pivotal means for supporting said yoke member on said axle housing for pivotal movement in a horizontal plane. second pivotal means supporting said spindle on said yoke member for pivotal movement in a vertical plane, with said two pivotal means being located substantially between said dual wheels, and means operatively connecting said dual wheels with said drive shaft including a dinerential mechanism carried on said` spindle.

6. A dual front wheel drive assembly including an axle housing, a driving shaft, a frame member, means supporting said frame member on said axle housing for pivotal movement'about a vertical axis, a spindlefor dual wheels, means supporting said spindle on said frame member for pivotal movement about a horizontal axis, and a gear unit pivotally movable with said spindle including a drivenshaft having the axis thereof in alignment with said vertical axis, means connecting said driven shaft with said drive shaft. and a differential mechanism operatively connecting said gear unit with said wheels.

f '1. A dual front wheel drive assembly including an axle housing, a supporting member on said axle housing having a pair of vertically spaced portions, pivotal means in each of said vertically spaced portions, a yoke supported on said two pivotal means for pivotal movement in a horiizontal plane, a spindle having a dual 'wheel car'- rying portion and a supporting portion, means pivotally connecting said supporting portion with said yoke for pivotal movement of said spindle in a vertical plane, a driven shaft rotatably mounted on said spindle supporting portion in vertical alignment' with said pivotal means, a gear on said driven shaft, a gear on said drive shaft in meshing engagement with said driven shaft gear, and means operatively connecting the dual wheels with said driven shaft gear.

8. A dual front wheel drive assembly including an axle housing, a drive shaft, a yoke member pivotally supported from said axle housing for movement about a vertical axis, a spindle having a supporting portion for dual wheels and a portion rotatably supported on said yoke member to provide fora pivotal movement of the spindle about a horizontal axis, means operatively connecting said dual wheels with said drive shaft including -a differential mechanism having a drivensleeve member `rotatably carried on said spindle wheel supporting portion, a plurality of rotatable gears angularly spaced about said sleeve member, a hub for one of said dual wheels having a gear portion rotatable on said sleeve member, and a hub for the other of ,said dual wheels having a gear portion rotatable on said sleeve member, with said plurality of rotatable gears being located between said two gear portions and in meshing engagement therewith.

9. A dual front wheel drive assembly including an axle housing, a drive shaft, a yoke member, pivotal means supporting said yoke member from said axle housing for pivotal movement in a horlzontal plane, a spindle for rotatably supporting dual wheels having a gear housing at one'end thereof, a second pivotal means pivotally connecting said housing with said yoke member to provide for pivotal movement of said spindle in a vertical plane, a drive shaft in said housing in co-axial alignment with said first pivotal means, gear means mounted on said shaft, a sleeve member rotatably supported on said spindle having a gear portion thereon, with said drive shaft. and gear portion being operatively connected with said gear means, and means connecting said 'dual wheels for driving by said sleeve member 

